基于超声-分光光度法的快速COD检测法研究

针对水质化学需氧量(COD)快速检测法稳定性差、检测条件要求高,应对突发水质事件反应慢的问题,提出了一种超声波辅助消解(UASD)作用下结合分光光度法(SP)的COD快速检测方法:UASD-SP法。通过超声波的空化作用在常温常压下快速消解待测水样;结合分光光度法检测消解后溶液得出COD值。用标准邻苯二甲酸氢钾溶液绘制工作曲线时,经UASD-SP方法测已知COD理论值的葡萄糖、乙酸、乙酸钠溶液的COD值的准确度在-2.7%~2.3%之间,并发现UASD法的水样最佳消解时间为4 min;采用UASD-SP法对实际污水样品(经稀释COD值500 mg/L)测得的COD值与国标法测值对比,其准确度在-5.4%~-2.1%之间,重复性RSD在0.42%~2.8%之间。     

快速消解分光光度法测定污水化学需氧量

建立快速消解分光光度法测定污水中的化学需氧量(COD)。通过对样品消解时间、消解温度、冷却时间及测定波长的验证,确定了最佳测定条件:消解温度为165℃,消解时间为10 min,检测波长为610 nm。同时,对该方法的成本进行了核算。COD质量浓度在50~1 000 mg/L的污水范围内与吸光度有良好线性关系,相关系数为1.000,方法检出限为10.5 mg/L。样品的加标回收率为98~102%,测定结果的相对标准偏差为0.45%~1.51%(n=6),每个样本的检测成本约3.18元。该方法快速、简便且成本低,可用于COD含量为50~1 000 mg/L的污水测定。     

快速消解分光光度法测定高氯废水中低浓度化学需氧量

建立快速消解分光光度法检测高氯废水中低浓度化学需氧量(COD)的方法。通过提高催化液中硫酸银的浓度(46 g/L)充分络合氯离子,同时降低消解液中重铬酸钾的浓度至0.061 2 mol/L来抑制重铬酸钾与氯离子的反应,达到有效消除Cl~–干扰的目的。水样在165℃消解30 min,于600 nm波长检测吸光度,标准曲线法计算COD。实验结果表明,水样中COD质量浓度为20 mg/L时,2 000 mg/L的Cl~–不干扰COD的测定(相对误差小于10%),并且随着COD质量浓度的增加,Cl~–产生的干扰误差逐渐降低。对国家环境保护部标准样品进行了测定,COD测定值与标准值一致。样品加标回收率为97.0%~103.7%,测定结果的相对标准偏差为2.01%~6.33%(n=6)。该法快速,有毒试剂用量小,成本低,具有较高的准确度和良好的精密度,可以用于多数工业废水中COD的测定。     

TiO2-KMnO4体系光催化氧化-光度法测定化学需氧量

基于纳米TiO2和KMnO4协同光催化氧化作用原理,建立了纳米光催化氧化体系测定化学需氧量(COD)的新方法.考察了测定化学需氧量的最佳条件,在含有0.1 g TiO2、 0.002 mol/L KMnO4的50 mL体系中,控温60 ℃,光照反应10 min,COD值在2.5～80 mg/L范围内与KMnO4吸光度变化值ΔA呈线性关系,其相应的线性方程为: ΔA=0.0023 ρ(COD) 0.0137,相关系数R=0.9977,COD值的检出限为1.5 mg/L.用该法测定地表水和自来水的COD值,相对标准偏差分别为1.9%和2.9%,标准加入回收率分别为100.5%和97.0%.     

一种新的光催化氧化体系用于化学需氧量的测定研究

基于KMnO₄能获得光生电子从而提高半导体光催化氧化能力的原理,建立了一种用纳米ZnO-KMnO₄协同体系光催化测定化学需氧量(COD)的新方法,探讨了催化氧化测定COD的机理,考察了测定COD的最佳反应条件.COD值浓度在1.5～10mg/L范围内与信号呈良好的线性关系,检测限为0.5mg/L.用本方法测定实际水样,结果和标准高锰酸盐指数法(COD_Mn法)相符.     

纳米PbO2修饰电极安培检测器流动注射法快速测定化学需氧量

采用以纳米PbO₂修饰电极为工作电极的安培检测器,用流动注射法快速检测水体中的化学需氧量(COD).根据纳米PbO₂修饰电极催化氧化电流的大小测定样品的COD值,在50-1 200 mg/L COD的范围内,电流响应与标准水样中的COD_Cr值呈线性关系,检出限为20 mg/L.该法不需对水样进行预处理,不使用有毒试剂,无二次污染,具有快速、简便、进样量少及工作电极使用寿命长等优点,与COD_Cr国家标准分析法对比具有较好的相关性.     

应用哈希COD测定仪测定废水中COD(高量程)方法的优化改进

通过考察消解时间、COD测定系统的酸度、重铬酸钾浓度对COD测定值的影响,确定了HACH-COD自配替代试剂的最佳操作条件(高量程)为:最佳的消解时间为60 min、H2SO4-硫酸汞的加入量为2.50 mL及重铬酸钾的浓度为1/6 K2Cr2O7=1.5 mol/L,样品分析的相对标准偏差(RSD)在1.0%以下,加标回收率在95.4%~107.7%之间。     

纳米石墨烯修饰电极电化学发光法测定盐酸氯丙嗪的研究

基于盐酸氯丙嗪对联吡啶钌电化学发光的增敏作用,以石墨烯(Graphene)和Nafion复合膜修饰的玻碳电极(GCE)为工作电极,建立了一种直接测定盐酸氯丙嗪的电化学发光新方法。最佳实验条件下,盐酸氯丙嗪浓度在8.0×10-7~1.2×10-4mol/L范围内与其相对发光强度呈良好线性关系(r=0.998 8),且在该修饰电极上的检出限(S/N=3)为4.0×10-7mol/L。连续测定4.0×10-6mol/L盐酸氯丙嗪溶液11次,发光强度值的相对标准偏差(RSD)为1.4%,表明该修饰电极具有较好的重复性和灵敏度。盐酸氯丙嗪的加标回收率为93%~104%,RSD(n=5)为4.1%。将该方法应用于药片中盐酸氯丙嗪的检测,结果满意。     

纳米石墨烯修饰电极电化学发光法测定盐酸氯丙嗪的研究

基于盐酸氯丙嗪对联吡啶钌电化学发光的增敏作用,以石墨烯(Graphene)和Nafion复合膜修饰的玻碳电极(GCE)为工作电极,建立了一种直接测定盐酸氯丙嗪的电化学发光新方法。最佳实验条件下,盐酸氯丙嗪浓度在8.0×10-7 ~1.2×10-4 mol/L范围内与其相对发光强度呈良好线性关系(r=0.998 8),且在该修饰电极上的检出限(S/N=3)为4.0×10-7 mol/L。连续测定4.0×10-6 mol/L盐酸氯丙嗪溶液11次,发光强度值的相对标准偏差(RSD)为1.4%,表明该修饰电极具有较好的重复性和灵敏度。盐酸氯丙嗪的加标回收率为93%~104%,RSD(n=5)为4.1%。将该方法应用于药片中盐酸氯丙嗪的检测,结果满意。     

芯片毛细管电泳电化学发光法快速测定盐酸普鲁卡因的含量

建立了芯片毛细管电泳电化学发光法快速测定盐酸普鲁卡因含量的新方法。采用三联吡啶钌(Ru(bpy)2+3)为电化学发光试剂,三电极体系(直径300μm的铂圆盘电极为工作电极,集成在铂圆盘工作电极外的钛管为对电极,Ag/AgCl丝为参比电极)进行检测。分别考察了运行缓冲溶液pH值、检测缓冲溶液pH值、检测电位以及分离电压对分离和检测性能的影响。在优化条件下,即运行缓冲溶液为10mmol/L磷酸盐溶液(pH4.0),检测池缓冲溶液为含5mmol/LRu(bpy)2+3的50mmol/L磷酸盐缓冲溶液(pH7.0),检测电位为1.25V,分离电压为300V/cm时,盐酸普鲁卡因可在40s内实现较好的分离与检测,其线性范围为10~2000μg/mL(r2=0.9991),检出限(S/N=3)为3.0μg/mL,加标回收率为97%~99%,相对标准偏差为1.8%~2.2%。该方法简便、快速、准确,可用于盐酸普鲁卡因注射液的质量控制。     

Sensitive Electrochemical Detection of Oxalate at a Positively Charged Boron‐Doped Diamond Surface

Allyltriethylammonium bromide (ATAB) was covalently attached to the surface of hydrogen‐terminated boron‐doped diamond (BDD) thin films using a photochemical method to fabricate positively charged electrode surfaces. The anodic current for oxalate oxidation both in cyclic voltammetry and in flow‐injection analysis with amperometry was found to be up to two times larger at ATAB‐modified BDD (ATAB‐BDD) than at an unmodified BDD electrode, which may be based on the electrostatic interaction between the oxalate anion and the electrode surface. In addition, the stability of the electrochemical detection of oxalate was improved at the ATAB‐BDD electrode compared to the unmodified electrode.     

Anodic Stripping Voltammetry of Heavy Metals at Nanocrystalline Boron‐Doped Diamond Electrode

Boron‐doped Diamond (BDD) electrode has become one of the important tools for heavy metal detection. By studying some analytical parameters of DPASV method, like deposition time and potential in different electrolyte concentrations (acetate buffer), the conditions for detecting very low metal ion levels (Zn, Cd, Pb, and Cu) could be chosen. Diluted electrolyte (0.01 M buffer) was one of the factors favoring low detection and quantification limits, but its quantification range is short in comparison to more concentrated media. For ?1.7 V deposition potential, the detection of single metal at ppb levels was reached in 60 s deposition time. Understanding different metal‐metal interactions shows the limits to the simultaneous determination of heavy metals at BDD. Quantification was possible for the simultaneous determination of Zn, Cd and Pb despite the overlapping of Zn and Cd peaks. The performance of the BDD was compared with that of another C‐based solid electrode: the glassy carbon electrode (without mercury plating). A lower base line current, wider potential range, higher sensitivity (3 to 5 times higher than GC) and longevity of the material were noticed for the BDD.     

Electrochemical Detection of Clenbuterol in Pig Liver at Pyrrole-DNA Modified Boron-doped Diamond Electrode

Introduction Clenbuterol { 4-amino-[( tert-butylamino) meth-yl]-3,5-dichlorobenzyl alcohol hydrochloride} is aβ-agonist drug[1]. It can improve the ratio of muscle tofat when it is administrated with high doses to ani-mals[2,3]. However, the residues of clenbuterol(CL)are toxic to humans, leading to sickness and possibleheart complication[4]. It has been reported that CL iseasy to accumulate in animal livers.Recently, some analytical methods for the detec-tion of CL, such as HPLC[5], GC…     

Boron‐Doped Diamond Electrode Coupled to Liquid Chromatography: Application to Simultaneous Determination of Benzodiazepines

The applicability of boron‐doped diamond (BDD) as a working electrode in an amperometric cell, coupled to HPLC, was demonstrated, for determining benzodiazepines in pharmaceutical preparations. The separation of the benzodiazepines was achieved using a Waters XTerra RP18 column (250×4.6 mm, 5 μm) with a mobile phase sodium phosphate (pH 3.5; 0.10 mol L^?1)‐acetonitrile (65 : 35, v/v) at flow of 1.2 mL min^?1. The measurements were performed in a system 871 Advanced Bioscan (Metrohm) with a BDD (8000 ppm) adapted to the thin layer mode cell. Stainless steel and platinum wire were used as reference and auxiliary electrodes, respectively. The cell was operated in pulse mode, using ?1.9 V as initial potential. The method presented linearity, repeatability and ruggedness and it represents a novel, alternative electroanalytical method for benzodiazepines determination.     

Electrochemical analysis of d-penicillamine using a boron-doped diamond thin film electrode applied to flow injection system

The electroanalysis of d-penicillamine in 0.1 phosphate buffer (pH 7) was studied at a boron-doped diamond thin film (BDD) electrode using cyclic voltammetry as a function of concentration of analyte and pH of analyte solution. Comparison experiments were performing using a glassy carbon (GC) electrode. The BDD electrode exhibited a well-resolved and irreversible oxidation voltammogram, but the GC electrode provided only an ill-defined response. The BDD electrode provided a linear dynamic range from 0.5 to 10 mM and a detection limit of 25 muM (S/B>/=3) in voltammetric measurement. It was also found that the peak potentials were decreased when the pH of the analyte solution was increased. In addition, penicillamine has been studied by hydrodynamic voltammetry and flow injection analysis with amperometric detection using the BDD electrode. The flow injection analysis results at the diamond electrode indicated a linear dynamic range from 0.5 to 50 muM and a detection limit of 10 nM (S/N approximately 4). The proposed method was applied to determine d-penicillamine in dosage form (capsules), the results obtained in the recovery study (255+/-2.50 mg per tablet) were comparable to those labeled (250 mg per tablet).     

Electrochemical analysis of -penicillamine using a boron-doped diamond thin film electrode applied to flow injection system

The electroanalysis of -penicillamine in 0.1 phosphate buffer (pH 7) was studied at a boron-doped diamond thin film (BDD) electrode using cyclic voltammetry as a function of concentration of analyte and pH of analyte solution. Comparison experiments were performing using a glassy carbon (GC) electrode. The BDD electrode exhibited a well-resolved and irreversible oxidation voltammogram, but the GC electrode provided only an ill-defined response. The BDD electrode provided a linear dynamic range from 0.5 to 10 mM and a detection limit of 25 μM (S/B≥3) in voltammetric measurement. It was also found that the peak potentials were decreased when the pH of the analyte solution was increased. In addition, penicillamine has been studied by hydrodynamic voltammetry and flow injection analysis with amperometric detection using the BDD electrode. The flow injection analysis results at the diamond electrode indicated a linear dynamic range from 0.5 to 50 μM and a detection limit of 10 nM (S/N≈4). The proposed method was applied to determine -penicillamine in dosage form (capsules), the results obtained in the recovery study (255±2.50 mg per tablet) were comparable to those labeled (250 mg per tablet).     

Cytochrome c biosensor for determination of trace levels of cyanide and arsenic compounds

An electrochemical method based on a cytochrome c biosensor was developed, for the detection of selected arsenic and cyanide compounds. Boron doped diamond (BDD) electrode was used as a transducer, onto which cytochrome c was immobilised and used for direct determination of Prussian blue, potassium cyanide and arsenic trioxide. The sensitivity as calculated from cyclic voltammetry (CV) and square wave voltammetry (SWV), for each analyte in phosphate buffer (pH = 7) was found to be in the range of (1.1–4.5) × 10⁻⁸ A μM⁻¹ and the detection limits ranged from 4.3 to 9.1 μM. The biosensor is therefore able to measure significantly lower than current Environmental Protection Agency (EPA) and World Health Organisation (WHO) guidelines, for these types of analytes. The protein binding was monitored as a decrease in biosensor peak currents by SWV and as an increase in biosensor charge transfer resistance by electrochemical impedance spectroscopy (EIS). EIS provided evidence that the electrocatalytic advantage of BDD electrode was not lost upon immobilisation of cytochrome c. The interfacial kinetics of the biosensor was modelled as equivalent electrical circuit based on electrochemical impedance spectroscopy data. UV–vis spectroscopy was used to confirm the binding of the protein in solution by monitoring the intensity of the soret bands and the Q bands. FTIR was used to characterise the protein in the immobilised state and to confirm that the protein was not denatured upon binding to the pre-treated bare BDD electrode. SNFTIR of cyt c immobilised at platinum electrode, was used to study the effect of oxidation state on the surface bond vibrations. The spherical morphology of the immobilised protein, which is typical of native cytochrome c, was observed using scanning electron microscopy (SEM) and confirmed the immobilisation of the cytochrome c without denaturisation.     

Electroanalysis of sulfonamides by flow injection system/high-performance liquid chromatography coupled with amperometric detection using boron-doped diamond electrode

Sulfonamides (SAs) were electrochemically investigated using cyclic voltammetry at a boron-doped diamond (BDD) electrode. Comparison experiments were carried out using a glassy carbon electrode. The BDD electrode provided well-resolved oxidation, irreversible cyclic voltammograms and higher current signals when compared to the glassy carbon electrode. Results obtained from using the BDD electrode in a flow injection system coupled with amperometric detection were illustrated. The optimum potential from a hydrodynamic voltammogram was found to be 1100 mV versus Ag/AgCl, which was chosen for the HPLC-amperometric system. Excellent results of linear range and detection limit were obtained. This method was also used for determination of sulfonamides in egg samples. The standard solutions of 5, 10, and 15 ppm were spiked in a real sample, and percentage of recoveries was found to be between 90.0 and 107.7.     

阿昔洛韦在硼掺杂金刚石电极上的电化学行为及其与DNA相互作用的研究

利用硼掺杂金刚石(BDD)电极通过循环伏安法和微分脉冲伏安法研究了阿昔洛韦在0.10 mol/L磷酸盐缓冲溶液(pH 7.4)中的电化学行为及其与DNA的相互作用.与玻碳电极相比,阿昔洛韦在BDD电极上的循环伏安曲线在1.17 V处的氧化峰电流更大,背景电流较低.根据峰电位随溶液pH值和扫描速率的变化趋势考察了阿昔洛韦...     

A flow injection method for the analysis of tetracycline antibiotics in pharmaceutical formulations using electrochemical detection at anodized boron-doped diamond thin film electrode

A method using flow injection (FI) with amperometric detection at anodized boron-doped diamond (BDD) thin films has been developed and applied for the determination of tetracycline antibiotics (tetracycline, chlortetracycline, oxytetracycline and doxycycline). The electrochemical oxidation of the tetracycline antibiotics was studied at various carbon electrodes including glassy carbon (GC), as-deposited BDD and anodized BDD electrodes using cyclic voltammetry. The anodized BDD electrode exhibited well-defined irreversible cyclic voltammograms for the oxidation of tetracycline antibiotics with the highest current signals compared to the as-deposited BDD and glassy carbon electrodes. Low detection limit of 10 nM (signal-to-noise RATIO = 3) was achieved for each drug when using flow injection analysis with amperometric detection at anodized BDD electrodes. Linear calibrations were obtained from 0.1 to 50 mM for tetracycline and 0.5–50 mM for chlortetracycline, oxytetracycline and doxycycline. The proposed method has been successfully applied to determine the tetracycline antibiotics in some drug formulations. The results obtained in percent found (99.50–103.01%) were comparable to dose labeled.